Many vehicles include a Passive Entry Passive Start (PEPS) system, also known as an Intelligent Access (IA) system, that enables vehicle entry and start capabilities without any physical handling of a traditional key or key fob by the driver or other vehicle user, as long as the user is carrying a valid key fob either on the user's person (e.g., in hand or in a pocket) or in a nearby belonging, such as a purse, jacket, or briefcase. The PEPS system typically includes a key fob with buttons or switches for enabling user-initiated control of various vehicle functions, including remote keyless entry (RKE) functions (e.g., locking and unlocking vehicle doors, opening and/or closing the trunk, tailgate, or sliding doors of the vehicle) and/or remote keyless ignition (RKI) functions (e.g., starting the vehicle engine in a non-motive mode that does not allow the vehicle to drive away). One or more of these key fob functions can be passively initiated by the PEPS system (i.e. without physical handling of the key fob) upon detecting certain conditions related to the key fob.
For example, existing PEPS system may perform key checks or other background tasks (i.e. without the user's knowledge) for detecting the presence of a key fob within a predetermined proximity of the vehicle, making sure a detected key fob is valid (e.g., linked to that vehicle), and/or determining the location of a valid key fob relative to the vehicle cabin (e.g., inside or outside the cabin). Based on the results of these key checks, the PEPS system may authorize a passive entry (e.g., unlocking the vehicle doors without requiring user-selection of an unlock button on the key fob), or a passive start (e.g., starting the vehicle engine in a motive mode that allows the vehicle to drive away in response to user-selection of an ignition button within the vehicle). The PEPS system may also perform background key checks in association with other vehicle functions that require the presence of the key fob for authorization purposes, such as “open sesame” or approach detection.
Given the ubiquitous nature of smartphones and other mobile devices in today's technology-driven world, some PEPS systems are further configured to include a Phone-as-a-Key (PaaK) feature, which enables the user's phone to function as the PEPS key fob and eliminates the need to carry a key fob for accessing and controlling the vehicle. For example, the PaaK feature allows the phone to be used for traditional key fob functions, such as unlock, lock, remote start, lift gate, and mobilization authorization, without the presence of a key fob.
While traditional PEPS key fobs use a Low Frequency (LF) receiver and an Ultra-High Frequency (UHF) transmitter to communicate with the vehicle, the PaaK feature is typically implemented using BLUETOOTH Low Energy (BLE) communications devices included in both the vehicle and the phone. However, BLE signals may be more prone to signal degradation due to reflection, absorption, and temperature shifts, as compared to the LF signals used to locate traditional PEPS key fobs, at least because of the difference in operating frequencies. For example, the LF signals are typically in the 125 kHz or 134.5 kHz bands, while the BLE signals are typically in the 2.4 GHz band. This fact of physics makes the PaaK device more difficult to locate than a traditional PEPS key fob.
Accordingly, there is still a need in the art for a PEPS system that can implement the PaaK feature with at least the same accuracy and dependability as traditional PEPS key fobs.